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Unit Code 300009:
Zinc Protoporphyrin, Blood

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Useful For

Evaluating iron deficiency

 

Monitoring treatment and environmental intervention of chronic

lead poisoning

Clinical Information

The porphyrins are intermediaries in the heme synthesis pathway.

 

When iron is not available for heme synthesis (eg, iron deficiency),

zinc protoporphyrin (ZPP) accumulates within red blood cells (RBC).

 

Lead inhibits several enzymes in the heme synthesis pathway and

causes increased levels of RBC ZPP.

 

ZPP is a biological marker of lead toxicity and was previously used,

in conjunction with blood lead assays, to screen for lead poisoning

in children. However, because of poor sensitivity and specificity,

ZPP is no longer recommended for lead screening in children.

However, ZPP remains a useful tool for monitoring treatment of

individuals with confirmed elevated lead levels.

Reference Values

<70 umol ZPP/mol heme

Interpretation

An elevated ZPP indicates impairment of the heme biosynthetic

pathway.

 

In children, a blood lead level of >20 ug/dL and an ZPP level

of >70 umol ZPP/mol heme are indicative of lead toxicity.(1)

 

Elevated ZPP levels in adults may indicate long-term (chronic)

lead exposure or may be indicative of iron deficiency anemia or

anemia of chronic disease.

Cautions

No significant cautionary statements

Clinical Reference

1. Stanton NV, Gunter EW, Parsons PJ, et al:  Empirically determined

     lead-poisoning screening cutoff for the Protofluor-Z hematofluorometer.

     Clin Chem 1989;35(10):2104-2107

 

2. Rosen JF:  Preventing Lead Poisoning in Young Children. US

     Public Health Service, Centers for Disease Control, Atlanta,

     GA, 1991

 

3. Occupational Safety and Health Administration:  OSHA Lead

     Standard - Requirements from the General Industry Standards

     Lead (1910, 1025), from 29 CFR 1910, 1025, A.M. Best Safety

     and Security - 2000. Retrieved March 2000. Available from URL:

     ambest.com/safety/osha/chap10g.html                          

 

4. Centers for Disease Control and Prevention. Screening Young

     Children for Lead Poisoning. Guidance for State and Local

     Public Health officials. Atlanta, GA: US Dept of Health and

     Human Services. Public Health Service: November 1997

     Available from URL:  cdc.gov/nceh/lead/guide/guide97.htm

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